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Nitrate processing filter issues (anti-algae device)

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Guess I will post again on the nitrate processing filter system from hell.

The problem is, from time to time (and it is happening far more of late) the biological processing nitrAte filter starts producing nitrItes, stops processing nitrates, and emits a strong sulfur odor; if I feed it before its due time the nitrites clear up and it starts to process nitrates again (but the odor, while less, is still there). Normal feeding is 15 ml of alcohol twice a week, but due to problems I have been adding 5 - 8 ml of alcohol between normal meal times. The nitrites signal then does disappear after a few hours but this whole problem does not make sense.

For those not familiar with these biological processing filters, the alcohol creates a large growth in the 'semi-oxygen' using bacteria that also consume nitrates. These nitrate consuming bacteria can only live in the mid-section of the sealed filter/processing chambers (they need water depleted in oxygen or they will die) - on the other hand, the nitrite processing bacteria require far higher levels of oxygen than the nitrate bacteria and hence don't grow in the region that gets the 'food' ( 70 proof alcohol.)

As such, the nitrite consuming bacteria should not care about the feeding for the filter's mid-section. The nitrite eating bacteria are only in the first stage of the filter where the high oxygenated water enters from the tank; besides, I'd assume alcohol would kill these types of bacteria. So, why is the filter acting this way - while it makes sense that the nitrates go away but why the nitrites???

Also, anyone with knowledge of these devices could help by offering input on why this filter is it no longer stable?

I do check the flow output of the filter (15 ml/18 sec) every two - three days and I adjust the flow as needed. I am getting tried of this nitrite signal (also, the nitrate processing does stop, as well.)

Still, this filter is what has helped stop all algae growth in my tanks perfectly (it is helped by an in tank algae scrubber) so I would like to figure this issue out.

Anyone with ideas on how to address the problem or ideas with this class of nitrate biological processing filter would be appreciated.

Knowledge is fun(damental)

A 75 gal with eight Discus, fake plants, and a lot of wood also with sand substrate. Clean up crew is down to just two Sterba's Corys. Filters: continuous new water flow; canister w/UV, in-tank algae scrubber!! Finally, junked the nitrate removal unit from hell.

I am going to cite Martin A Moe from his book The Marine Aquarium reference. Page # 259 Chapter 4.

Denitrification is the opposite of nitrification. It uses chemoheterotrophic bacteria ( chemical eating bacteria) in an oxygen poor environment to reduce notrate to nitrate themn to nitrous oxide, then to nitrogen gas which is vented from the filter. The bacteria are able to operate in the absence of oxygen by using nitrate as the terminal electron receptor. These bacteria are present in the bacteria population and do not need to be seeded.

Batch denitrification:
This method is used to treat a small amount of water and isolates it from flow. A ten to twenty percent lactose or glucose solution or alcohol may be used. Vodka. one to two ounces of food per 10 gallons of batch water.

It seems to me from reading through various references that the application of a food product in the form of an alcohol or other chemical feed to react upon nitrate requires a batch system which isolates the waters until they are reacted upon. One of the elements most critical is venting which will allow the gas to escape.

My opinion on why the filter destabilized is that it has leeched alcohol into the other areas or zones of gas exchange or that the amounts of nitrate nitrite per zone have fluctuated causing a population shift in the bacterial populations. It may be as simple as providing proper gas exchange venting to the areas in which the anaerobic bacteria live and providing oxygen via an air tube into the aerobic zones. If each zone is not properly vented and oxygenated the boundaries will become skewed and the various bacterial populations will over lap. There is a something wrong with the design or the interpretation of the filter as the injection of alcohol is done into a bacteria that does not need oxygen or oxygenated water flow. This oxygen presence interferes with the chemistry being done within the unit and the alcohol is not properly reacted upon in the presence of free oxygen.

Any of the works of Moe, Theil or Sprung covering denitrification devices should help you greatly.

I can only comment based on what I have learned with a similar concept applied in a marine set-up, which is not completely the same as your set-up you are talking about here. Getting the correct dosing level for on going use might be a part of the problem here. How did you determine the above amount of 15ml twice a week ?

If you take your time to do the research FIRST, you can successfully set-up and keep ANY type of aquarium with ease."Not using a quarantine tank is like playing Russian roulette. Nobody wins the game, some people just get to play longer than others." - Anthony CalfoFishless CycleCycling with FishMarine Aquarium Info [URL="http://saltwater.aquaticcommunity.com/"]